A U.S. congressional panel is set to vote on declaring that the 1915 massacre of more than a million Armenians by Ottoman Turks was genocide. But Turkey warns that such a move could harm U.S.-Turkey relations.

The resolution, being considered by the U.S. House of Representatives Foreign Affairs Committee, would call on the U.S. president to ensure that American foreign policy refers to the mass killing of Armenians by Turkey's then Ottoman rulers as genocide. Armenians say that as many as 1.5 million perished. But Ankara says far fewer died and that they were killed in a civil war in which Turks also died.

"Turkey and the United States are two important allies," he said. "We have a shared history over the past 50-60 years. Adopting this resolution will harm relations."

In a rare show of unity, a powerful Turkish bipartisan parliamentary group is in Washington to deliver that message. But they are facing an uphill battle.

Although President Barack Obama is on record as supporting the recognition of the killings as genocide, he avoided using that term in front of his hosts last year while visiting Turkey.

Instead, Mr. Obama emphasized the need to improve relations between Turkey and Armenia. He pointed to hopes for a breakthrough to ease long-standing tensions.

"What I would like to do is to encourage [Turkish] President [Abdullah] Gul to move forward with what have been some very fruitful negotiations," said President Obama. "And I am not interested in the United States in anyway tilting these negotiations one way or another while they are having useful discussions."

Last October, the president of Turkey and Armenia signed a protocol committing to normalizing relations and working to resolve the historical dispute. Ankara has warned that the U.S. Congress passing the genocide resolution could seriously undermine those efforts.

But analysts say that efforts to normalize relations have grounded to a halt, with neither country's parliament ratifying the protocol.

Political scientist Cengiz Aktar of Istanbul's Bahcesehir University:

"I don't think the Turkish government is serious enough on ratifying the protocol because the reason they evoke to block the ratification process in the parliament is not serious," said Cengiz Aktar. "I think, unfortunately, [this is] yet another missed opportunity."

"There would be important implications," said Egemen Bagis. "Turkey today provides 70 percent of all the logistical goods to all the U.S. troops in Iraq. Turkey is an important player in NATO. We have the second largest military in NATO. We are together in most of the peacekeeping operations."

And with Turkey bordering Iran, analysts say it stands to play a crucial role in enforcing new, tougher sanctions against Tehran for its nuclear program. Turkey also plays an important military and diplomatic role in Afghanistan.

"Turkey, who has difficult relationship with the EU, can hardly antagonize yet another Western entity, that is the United States," said Aktar. "So what is left really? So it's just rhetoric."

But with Turkey playing an important role in so many key areas of U.S. foreign policy, some analysts caution that calling Ankara's bluff could be risky. A vote by the House Foreign Affairs Committee could come as early as Thursday (3.4.10).